Environmental Health Is Going to Get Very Personal

Raghu G. Mirmira, MD, PhD

Earth Day 2022 has come — and gone. Gone, because the day has passed, and for many, so has the message. Earth Day is a call to action not just for a day but for a lifetime.

If you reflect on the awful global events that we've witnessed in recent years — cataclysmic floods, wildfires, extreme heat waves, melting of polar ice — you're probably thinking that governments need to act, and hopefully the Greta Thunbergs of this world or the Paris Agreement will eventually have an impact.

Beyond these more obvious consequences of climate change, there are environmental effects on our everyday health. As healthcare providers, we see these effects daily in the work we do, but maybe we don't recognize them — perhaps because we are often trained to see them as a consequence of the lifestyles people lead, as genetic predispositions, or maybe just as bad luck.

We are in the midst of a new era in healthcare where we must factor in more than just the biological determinants of disease. Our community, personal behaviors, psychological factors, and environmental exposures are arguably factors that weigh heavily in disease risk and healthcare accessibility.

Environmental Exposures Not Easily Quantifiable

At the University of Chicago's Institute for Translational Medicine, these other health determinants have been collectively termed the "sociome." The problem with the sociome — and environmental exposures in particular — is that, unlike biological determinants of disease, it has no easily quantifiable measure, sometimes questionable contribution to disease, and can be so embedded within communities that it may not be obvious (think lead poisoning).

Sadly, even when we recognize a contribution of the sociome to a disease, we often dismiss it as not easily modifiable. The environment is one that is particularly notorious because we take it as a fact of life and assume that there is little that any one person can do about it. But when you think about any given disease, you realize that the data make a compelling case that personal health and the environment are closely linked.

Obesity and Reduced Physical Activity Affect the Environment

Obesity is, by all measures, epidemic. According to the Centers for Disease Control and Prevention, obesity affects more than 40% of the US population. The consequences of obesity include diabetes, cardiovascular disease, and cancers, as well as worse COVID-19 outcomes.

Within this context lie health disparities within underserved populations, which face disproportionate burdens of obesity. In particular, the lack of availability of healthy foods in many underserved communities leads to the provision of cheap, calorie-dense alternatives (and, yes, calories do matter when it comes to obesity).

Agriculture practices focused on the production of heavily processed foods account for a staggering one third of greenhouse gas emissions worldwide. Increasing appetite for meats, for example, underlies worldwide trends of deforestation to make room for cattle ranching and is unarguably the impetus for the ongoing loss of the Amazon biome.

Of course, obesity is not driven only by food consumption and food choices. Reduced physical activity resulting from use of motorized vehicles, in particular, reduces energy expenditure at the expense of increasing greenhouse gas emissions. In one study, it was shown that cycling to work just 1 day per week can reduce an individual's greenhouse gas emissions by over 65% — and cycling to work can have the same effect as dedicated exercise periods on weight loss and obesity. A win-win.

Environmental-Associated Disorders

Multiple other diseases are also closely linked to the environment. Particulate matter of 2.5 microns or less in size (known as PM_2.5) is often used as a quantitative measure of environmental air pollution. Perhaps everyone knows that exacerbation of lung diseases such as asthma is closely linked to the prevalence of PM_2.5 in the atmosphere.

But less appreciated are other disorders or deficiencies that we don't normally associate with the environment. For example, vitamin D deficiency is closely linked to PM_2.5 exposure. And, relevant to the ongoing pandemic, vitamin D deficiency is associated with more severe COVID-19. Other disorders linked to PM_2.5 levels include low birth weight (and did you know that low birth weight is a risk factor for obesity in adulthood?), thyroid disorders, infertility (think about the alarmingly diminishing rates of global fertility), and certain kinds of cancers.

So, where does this link between health and the environment leave us? The enormity of the effects of the environment on health is enough to make you feel a personal sense of futility. That's a justifiable feeling. As individuals who care about health, imagine instead doing your part by reducing your own carbon footprint — for your own health, if not for others'.

If you are a healthcare provider, spend a few minutes talking with your patients about the advantages of reducing their carbon footprints. It's simple enough. How about walking or cycling to work 1 day a week, or just working from home once a week? We've already seen the global impact from work-at-home policies introduced during the pandemic — a striking global reduction in PM_2.5— so we know this works, but at the personal level you know you are doing your part (not to mention the health benefits of walking or cycling).

Also, while no one is asking that you become vegan, think about reducing meat and dairy intake; a diet that meets World Health Organization recommendations is estimated to reduce greenhouse gas emissions by 17%.

How about leveraging nontraditional sources of protein (culture-grown meats and insect-based supplements)? These alternatives may not sound palatable today, but perceptions change with time. Some of these interventions are easier for some people than for others, and we need to be mindful of cultures and socioeconomic status. But there is always common ground, and framing environmental issues around personal health often achieves agreement. So, as we reflect upon Earth Day 2022, its theme of "invest in our planet" is as much about our health today as it is about the future of our planet.

Raghu Mirmira, MD, PhD, is professor of medicine at the University of Chicago and director of the Translational Research Center, which focuses on moving fundamental concepts of health from the laboratory to the clinic. He is one of the leading NIH-funded diabetes and obesity investigators in the United States and is author of more than 170 scholarly articles on the production of insulin and its effects on organ systems. Follow Raghu on Twitter: @rmirmira

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